Carrillo N
Eur J Biochem. 1985 Aug 1;150(3):469-74. doi: 10.1111/j.1432-1033.1985.tb09045.x.
Biosynthesis of ferredoxin-NADP+ reductase in higher plants was investigated in relation with the mechanism of formation of the holoenzyme. The putative precursor of the flavoprotein, obtained after cell-free translation on a wheat germ extract primed with poly(A)-rich mRNA, was able to spontaneously bind free FAD, rendering a functional prereductase. The newly synthesized preholoenzyme showed diaphorase and cytochrome c reductase activities, an apparent molecular mass of 45 kDa, and contained FAD as the only flavin cofactor. It gave a positive reaction towards antisera against mature ferredoxin-NADP+ reductase. On the other hand, intracellular distribution of flavin-synthesizing enzymes indicates that FAD formation occurs in the cytoplasm; that is, in the same compartment as the site of reductase synthesis. On the basis of the preceding data a model is presented for the biosynthesis of the enzyme in vivo, involving conjugation of the apoprotein with FAD in the cytoplasm, followed by transport of the preholoreductase across the chloroplast envelope to reach its final destiny in the thylakoid membrane.
对高等植物中ferredoxin-NADP⁺还原酶的生物合成与全酶形成机制进行了研究。在用富含多聚腺苷酸的mRNA引发的小麦胚芽提取物中进行无细胞翻译后获得的黄素蛋白假定前体，能够自发结合游离FAD，形成有功能的前还原酶。新合成的前全酶具有黄递酶和细胞色素c还原酶活性，表观分子量为45 kDa，且仅含有FAD作为黄素辅因子。它对针对成熟ferredoxin-NADP⁺还原酶的抗血清呈阳性反应。另一方面，黄素合成酶的细胞内分布表明FAD的形成发生在细胞质中，也就是说，与还原酶合成位点在同一区室。基于上述数据，提出了该酶在体内生物合成的模型，包括脱辅基蛋白在细胞质中与FAD结合，随后前还原酶通过叶绿体被膜转运，在类囊体膜中到达其最终位置。
